Toby Jones (“Captain America: The First Avenger”) and Sian Brooke (“Under the Greenwood Tree”) round out the primary cast as the newly introduced villains Culverton Smith and Eurus.

Fans of the show have waited three full years for the new season of “Sherlock,” and after watching season four, they are bound to be disappointed.

The season is not necessarily bad: as a work of art, the show emerges as a shining, unrivaled example of the cinematic beauty and elegance that television as a medium is capable of.

Moffat and Gatiss experiment with striking, surreal, even psychedelic imagery and cinematography, introducing fantastic sequences that make the viewer feel as though they are watching a high-budget blockbuster movie, not a British drama show on PBS or BBC. In this sense, the season is a natural progression of Moffat and Gatiss’ Christmas special, “The Abominable Bride,” which premiered in early 2016.

The earlier special drags the viewer into the depths of Sherlock’s mental torment and human weakness. The new season simply expands the scope of this exploration, confronting the viewer with the weakness and fallibility of every character.

The main creative goal of the new season is demonstrating that cleverness of any magnitude is no guarantee of emotional strength or moral discipline. If Sherlock and Moriarty are the prototypical sociopaths of different ethical persuasions, Eurus is the ultimate deranged genius.

While the season begins a bit slowly, it reaches new artistic heights by the third episode, in which Cumberbatch and Louise Brealey (“Casualty”) turn in emotionally convincing performances.

In a show with dialogue normally characterized by detached, witty banter, these portrayals were remarkable deviations from the norm.

Though this development marks season four of “Sherlock” as undeniably superior to previous seasons as a television drama, fans of the show do not necessarily want drama, art, or experimental cinematography: they want “Sherlock.”

As impressive as it may be, the latest season is a significant departure from the character of the show in previous seasons. Herein lies the problem with Moffat and Gatiss’ new work: it is simply
too new.

While “The Abominable Bride” departed stylistically from earlier installments of the show in the same way season four does, its content continued in the direction of former seasons, unlike
season four.

The special gave viewers pure, classic “Sherlock,” returning to the “crime-solving duo” format. Season three had departed from this scheme, and the return to the era that gave birth to the beloved character
was successful.

Because the new filming style was not entirely well-received, “The Abominable Bride” shook viewers’ confidence in Moffat and Gatiss, but season four is bound to destroy previous criticsm.

The first episode of the season seems to be taken straight from a spy show, and the third and final episode feels like a rehashed “Saw” movie.

While the second episode offers a temporary reprieve, giving viewers another chance to see Holmes and Watson working together to defeat a nemesis, the broader story-arc of the season
becomes problematic.

No longer does the show follow a detective and his doctor-sidekick battling London’s greatest criminals for their own entertainment. Rather, the show is about personal conflict and emotional development, great themes for a television drama, but not for “Sherlock” fans.

Though the omnipresent spectre of Moriarty, practically taunting viewers with the prospect of a showdown, haunts the season, no classic endgame ever comes.

“Sherlock,” no matter how thrilling and dramatic it may now be, is no longer the series the fans have grown to love.

If hardcore fans are to find any bright spot in the new season, it will come at the end of the third episode. The conclusion of the season suggests that the show will return to its roots, but any hope for the future is dampened by a sense that the conclusion serves as a farewell.

Given Cumberbatch and Freeman’s hectic filming schedules, it is not certain if a fifth season is feasible. Fans cannot be assured that Holmes and Watson will return to their former glory on the small screen.